1. Field of the Invention
The present invention relates to a scanning system or more in particular to a scanning system for scanning a multiplicity of points in matrix form column by column.
2. Description of the Prior Art
In the scanning system of this type, the access time, that is, the time interval from the time point when the columns of points to be scanned begin to be scanned until the time point when the information on such columns is obtained is long compared with the working time of the central controller, partly due to the delay time caused by a noise-eliminating filter of a sense-amplifier and partly due to the stray capacitance of a scanning drive line connecting the columns of points to be scanned to a scanning driver or a read line, that is, a bus connecting the columns to be scanned to the sense-amplifier, resulting in a lower efficiency of the central controller which suspends its operation during the access time.
A scanning device which requires a short access time, on the other hand, commonly uses a bus scanning system in which means are provided for preventing noise from being carried on the bus and for increasing the noise tolerance of the sense-amplifier without any noise-eliminating filter, thus leading to the disadvantage of a higher cost.